#include <errno.h>
#include <libgen.h>
#include <fcntl.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/eventfd.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>

#include <linux/ioctl.h>
#include <linux/vfio.h>
#include <linux/pci_regs.h>

void usage(char *name)
{
	fprintf(stderr, "usage: %s <ssss:bb:dd.f>\n", name);
	fprintf(stderr, "\tssss: PCI segment, ex. 0000\n");
	fprintf(stderr, "\tbb:   PCI bus, ex. 01\n");
	fprintf(stderr, "\tdd:   PCI device, ex. 06\n");
	fprintf(stderr, "\tf:    PCI function, ex. 0\n");
}

int main(int argc, char **argv)
{
	int seg, bus, slot, func;
	int ret, container, group, device, groupid;
	char path[50], iommu_group_path[50], *group_name;
	struct stat st;
	ssize_t len;
	void *map = MAP_FAILED;
	int i;
	unsigned int bar;
	struct vfio_group_status group_status = {
		.argsz = sizeof(group_status)
	};
	struct vfio_region_info region_info = {
		.argsz = sizeof(region_info)
	};
	struct vfio_region_info config_info = {
		.argsz = sizeof(config_info)
	};
	struct vfio_iommu_type1_dma_map dma_map = {
		.argsz = sizeof(dma_map),
		.flags = VFIO_DMA_MAP_FLAG_READ | VFIO_DMA_MAP_FLAG_WRITE,
	};

	if (argc != 2) {
		usage(argv[0]);
		return -1;
	}

	ret = sscanf(argv[1], "%04x:%02x:%02x.%d", &seg, &bus, &slot, &func);
	if (ret != 4) {
		fprintf(stderr, "Invalid device\n");
		usage(argv[0]);
		return -1;
	}

	/* Boilerplate vfio setup */
	container = open("/dev/vfio/vfio", O_RDWR);
	if (container < 0) {
		fprintf(stderr, "Failed to open /dev/vfio/vfio, %d (%s)\n",
		       container, strerror(errno));
		return container;
	}

	snprintf(path, sizeof(path),
		 "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/",
		 seg, bus, slot, func);

	ret = stat(path, &st);
	if (ret < 0) {
		fprintf(stderr, "No such device\n");
		return ret;
	}

	strncat(path, "iommu_group", sizeof(path) - strlen(path) - 1);

	len = readlink(path, iommu_group_path, sizeof(iommu_group_path));
	if (len <= 0) {
		fprintf(stderr, "No iommu_group for device\n");
		return -1;
	}

	iommu_group_path[len] = 0;
	group_name = basename(iommu_group_path);

	if (sscanf(group_name, "%d", &groupid) != 1) {
		fprintf(stderr, "Unknown group\n");
		return -1;
	}

	snprintf(path, sizeof(path), "/dev/vfio/%d", groupid);
	group = open(path, O_RDWR);
	if (group < 0) {
		fprintf(stderr, "Failed to open %s, %d (%s)\n",
		       path, group, strerror(errno));
		return group;
	}

	ret = ioctl(group, VFIO_GROUP_GET_STATUS, &group_status);
	if (ret) {
		fprintf(stderr, "ioctl(VFIO_GROUP_GET_STATUS) failed\n");
		return ret;
	}

	if (!(group_status.flags & VFIO_GROUP_FLAGS_VIABLE)) {
		fprintf(stderr,
			"Group not viable, all devices attached to vfio?\n");
		return -1;
	}

	ret = ioctl(group, VFIO_GROUP_SET_CONTAINER, &container);
	if (ret) {
		fprintf(stderr, "Failed to set group container\n");
		return ret;
	}

	ret = ioctl(container, VFIO_SET_IOMMU, VFIO_TYPE1_IOMMU);
	if (ret) {
		fprintf(stderr, "Failed to set IOMMU\n");
		return ret;
	}

	snprintf(path, sizeof(path), "%04x:%02x:%02x.%d", seg, bus, slot, func);

	device = ioctl(group, VFIO_GROUP_GET_DEVICE_FD, path);
	if (device < 0) {
		fprintf(stderr, "Failed to get device\n");
		return -ENODEV;
	}

	config_info.index = VFIO_PCI_CONFIG_REGION_INDEX;
	ret = ioctl(device, VFIO_DEVICE_GET_REGION_INFO, &config_info);
	if (ret) {
		fprintf(stderr, "Failed to get config space region info\n");
		return ret;
	}

	for (i = 0; i < 6; i++) {
		if (pread(device, &bar, sizeof(bar),
		          config_info.offset + PCI_BASE_ADDRESS_0 + (4 * i)) !=
		    sizeof(bar)) {
			fprintf(stderr, "Error reading BAR%d\n", i);
			return -errno;
		}

		if (!(bar & PCI_BASE_ADDRESS_SPACE)) {
			break;

tryagain:
			if (bar & PCI_BASE_ADDRESS_MEM_TYPE_64)
				i++;
		}
	}

	if (i >= 6) {
		fprintf(stderr, "No memory BARs found\n");
		return -ENODEV;
	}

	region_info.index = VFIO_PCI_BAR0_REGION_INDEX + i;
	ret = ioctl(device, VFIO_DEVICE_GET_REGION_INFO, &region_info);
	if (ret) {
		fprintf(stderr, "Failed to get BAR%d region info\n", i);
		return ret;
	}
  
	if (!(region_info.flags & VFIO_REGION_INFO_FLAG_MMAP)) {
		printf("No mmap support, try next\n");
		goto tryagain;
	}

	if (region_info.size < getpagesize()) {
		printf("Too small for mmap, try next\n");
		goto tryagain;
	}

	map = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE,
		   MAP_SHARED, device, region_info.offset);
	if (map == MAP_FAILED) {
		fprintf(stderr, "Error mmap'ing BAR: %m\n");
		goto tryagain;
	}

	dma_map.size = getpagesize();
	dma_map.vaddr = (__u64)map;
	dma_map.iova = 1024 * 1024 * 1024; /* 1GB IOVA, arbitrary */

	ret = ioctl(container, VFIO_IOMMU_MAP_DMA, &dma_map);
	if (ret) {
		fprintf(stderr, "Failed to DMA map: %m\n");
		return ret;
	}
		
	printf("Passed\n");
	return 0;
}